【作者】 徐雪峰；

【导师】 蔡跃波；

【作者基本信息】 南京水利科学研究院 ， 材料学， 2006， 硕士

【摘要】 混凝土高效减水剂已成为高性能混凝土和商品混凝土的一个必需组分，其中被称为第三代混凝土高效减水剂的聚羧酸系减水剂由于具有减水率高、坍落度保持性好等众多优点已成为国内外研究的一个重要方向。本文在总结以往学者的相关研究基础上，探索出一条国内未见报道的聚羧酸减水剂合成新途径。 根据聚羧酸系减水剂的作用机理，本文设计了以丙烯酸类聚合物作为高分子主链，主链上接枝有羧基、磺酸基、酯基或聚醚长侧链的分子结构。为此，本文设计了五套研究方案，通过这五套方案所得产品的水泥净浆流动度性能对比，最终选择了先以丙烯酸、甲基丙烯磺酸钠等单体在聚醚介质中共聚，然后在同一反应釜中，在催化剂作用下进行缩合反应的一步法合成方案。 采用正交设计法进行配方优化试验，确定了影响减水剂性能的关键因子。实验表明：羧基与醚键的摩尔比率和聚醚侧链的聚合度是分子结构中的关键因子；缩合时间和聚合时间是聚合工艺中的关键因子，引发剂用量和链转移剂用量是第二重要的影响因子。按择优配方合成的减水剂代号为NKY1。 对掺有NKY1的混凝土性能进行了试验研究，重点分析讨论了其具有良好混凝土坍落度保持性能的机理。试验结果表明：掺NKY1的混凝土减水率可达30％，1小时混凝土坍落度损失可控制在10％以内，2小时混凝土坍落度损失可控制在23％以内。 通过化学分析和仪器分析对合成的聚羧酸分子结构进行了表征。化学分析是通过测定系统中碳碳双键的变化监控高分子共聚反应进程，通过测定系统中酸值的变化监控高分子的酯化反应进程。仪器分析是通过红外光谱和凝胶渗透色谱分析分子的结构，红外光谱分析结果表明：NKY1减水剂中含有羧基、磺酸基、酯基和醚键，但尚不能确定聚醚长侧链是否已经接枝上主链。缩合反应前后的凝胶渗透色谱图结果显示：经缩合反应后生成了一重量分数很大的物质，且该物质峰位值明显向左偏移，说明分子量显著增大，至此可以确定，聚醚长侧链已经接枝到主链上。更多还原

【Abstract】 High range water-reducing admixtures have been the essential component in High Performance Concrete and Ready-mixed Concrete. Especially, the research and development of polycarboxylic acid type water-reducers has been one of important direction in worldwide because of their excellent rate of water-reducing and prevention of slump loss. Polycarboxylic acid type water-reducers have been called as the third-generation superplasticizer. Based on the summary of the existing research results, a new method of synthesizing the polycarboxylic acid type water-reducer has been investigated in this paper.According to the working principle of polycarboxylic acid type water-reducers, Acrylic acid is selected as macromolecular main chain on which there are carboxylic groups, sulphonic groups, ester groups or long side chains of polyether groups. In order to realize this molecular designing, five test schemes were designed in this paper. Based on the comparison of the fluidity of cement paste, the scheme in which monomers such as acrylic acid and methacrysulphnic sodium were polymerized in medium of polyether, and then polyether was grafted to the main chain by condensation reaction with the catalyst was adopted at last.Based on the orthogonal experimental design, the key factors influencing the performance of water reducer have been ascertained in the scheme optimization test. It was found that molar rate of carboxylic groups and ether groups and the degree of polymerization of polyether side chain are key factors in the radical polymerization; reaction time is the key technical factor of the condensation reaction while the amount of initiator and chain transfer additives are the second important factors. The water-reducer synthesized by the optimized method is named ;as NKY1.The performance of concrete mixed with NKY1 was studied, with emphasis on analysis and discussion the mechanism of good ability of prevention of slump loss. The test result shows that the water-reducing rate of the concrete mixed with NKY1 can reach 30%, and its slum loss can be controlled in 10% in 1 hour and 23% in 2 hours.Chemistry analysis and apparatus analysis were used to characterize the更多还原